Differential and collective rotor blade pitch control for convertiplane



Jan 7, 1958 N. J. MEDVEDEFF DIFFERENTIAL AND COLLECTIVE ROTOR BLADE PITCH CONTROL FOR CONVERTIPLANE 4 Sheets-Sheet 1 Filed Jan. 18, 1954 3mm 7, 1958 N. J. MEDVEDEFF DIFFERENTIAL AND COLLECTIVE ROTOR BLADE PITCH CONTROL FOR CONVERTIPLANE 4 Sheets-Sheet 2 Filed Jan. 18, 1954 .I fiw f g am QA W 8 Q\\ T m w hmx m$ M W1 1 In T4. WTfI- T I I I M Tm Qmf MM, ww, I Q 3 mm I m {a Q 3w 3 W mm Jan. 7, 1958 N. J. MEDVEDEFF DIFFERENTIAL AND COLLECTIVE ROTOR BLADE PITCH CONTROL FOR CONVERTIPLANE 4 Sheets-Sheet 3 Filed Jan. 18, 1954 O O a I///// H h H mm 7 a MN! v ml Q 1 llllll ll mg Q 5 I Q Q. m\ I: M Q m6 k IOS 9k QQ\ orssr n 1958 N. J. MEDVEDEFF 2,819,029

DIFFERENTIAL AND COLLECTIVE ROTOR BLADE PITCH CONTROL FOR CONVERTIPLANE Filed Jan. 18, 1954 4 Sheets-Sheet 4 Iwezziofl:

NMoZcas el,

United States Patent 2,819,029 Patented Jan. 7, 1958 DIFFERENTIAL AND COLLECTIVE ROTOR BLADE PITCH CONTRGL FOR CONVERTIPLANE Nicholas J. Medvedeif, Hanover, Mass.

Application January 18, 1954, Serial No. 404,501

9 Claims. (Cl. 244-4) This invention relates to convertiplanes of the type described and claimed in my co-pending application, Serial No. 337,783 filed February 19, 1953, now Patent No. 2,738,146.

In. the operation and control of a convertiplane, it is desirable that the hand and foot controls that are manipulated by the pilot should operate in the same general manner as the controls found in conventional planes so as to make it as easy as possible for pilots of conventional planes to learn to fly a convertiplane.

In a conventional airplane the control stick is moved to the right to raise the left wing and to the left to raise the right wing. If it is desired to have the plane climb, the pilot customarily pulls back on the stick and to descend, he pushs forward on the stick.

Accordingly, it is proposed in the present invention to provide control levers which when moved sidewise or forward and backward will produce substantially the same type of behaviour in a convertiplane.

To correct for roll in a convertiplane when the helicopter blades are in operation, it is necessary that the rotor on the low side exert more lift than the rotor on the high side. This may be accomplished either by speeding up the low side rotor in relation to the high side rotor or by providing rotors in which the pitch of the blades may be varied. In the present disclosure, there will be shown and claimed rotor blades in which the pitch may be varied by new and novel mechanism.

When the convertiplane is in operation with the lift being supplied by the rotors, the lift may be increased by simultaneously increasing the pitch of the rotor blades, and conversely, the lift may be decreased by simultaneously decreasing the pitch of the rotor blades. In other words, the controls are arranged in such manner that pulling back on the stick will increase the pitch of the rotor blades causing the machine to rise and pushing forward on the stick will decrease the pitch of the blades causing the machine to settle.

It will be understood from the foregoing that the present invention is applicable to convertiplanes having rotors which are mechanically operated by shafting and gearing with the power supplied by the engine which operates the conventional airplane propeller or by a separate engine if such is preferred, and to a convertiplane in which the rotors are jet driven.

In the present disclosure the rotor is shown as being driven by jets, but this is not to be considered as limiting in any way the invention which resides in the means for controlling the pitch of the rotor blades to correct for roll or to vary the lift. In correcting for roll the pitch of the blades of one rotor is increased and the pitch of the blades of the other rotor is decreased whereas in varying the lift the pitch of the blades of both rotors are simultaneously increased or decreased.

Another object of the invention is the provision of novel means for stopping the rotation of the rotors and locking them in proper tranverse position so that they may be moved to stowed position against the side of the fuselage. The invention herein disclosed includes a brake which may be applied by hand to initially stop the rotors, a hydraulic motor which may be actuated thereafter to move the rotors to correct transverse position and a locking mechanism efiective to hold the rotors in proper position while they are being moved to stowed position.

These and other objects of the invention will become more apparent as the description proceeds with the aid of the accompanying drawings in which:

Fig. l is a front view of a convertiplane with the right half showing the rotors in extended position to function as a helicopter and the left half showing the rotor retracted when the machine is functioning as a conventional airplane.

Fig. 2 is a side elevation from the left of Fig.1 showing the starboard rotor in stowed position.

Fig. 3 is an elevation looking from the front toward the rear showing details of the construction which permits simultaneous or differential change in the pitch of the rotor blades.

Fig. 4 is a plan View of most of the mechanism disclosed in Fig. 3.

Fig. 5 is an enlarged vertical sectional view of the mechanism at the right of Figs. 3 and 4.

Fig. 6 is a. plan view partly in section of the control for varying the lift.

Fig. 7 is an enlarged front elevation of the two manual controls looking to the rear toward the pilot, that on the left (on the pilots right) for controlling lift, and that on the right (on the pilots left) for correcting roll.

Fig. 8 is a view of the hydraulically operated braking system.

In the description and claims which follow, it will be understood that when the term rotor is used, it contemplates as part thereof the rotor blades. The mechanism shown for actuating the baldes to produce collective or differential blade movement includes fluid control means, but mechanical means could readily be substituted if desired.

Means for varying the pitch of the rotor blades Referring to Fig. 3 which is a view looking from the front to the rear of the convertiplane, Fig. 4 which is a plan view of most of Fig. 3 and Fig. 5, there is shown a wing 2 and a portion of the fuselage which is numbered 4, d, it and it). To the wing and fuselage is connected a truss structure comprising a front leg 12, a rear leg 14 and a short leg 16 connecting the inner ends of legs 12 and This structure is connected to the fuselage by a bushing 13 which extends through a bearing 20 which bushing is connected with gearing 22 and a hydraulic motor 24%. At the other end of leg 16 is a short arm 26 having a roller 28 on its end which is designed to slide in a curved U-shaped track 3 That is, as the truss leg 16 may be caused to swing in an are about the pivot 18 through the actuation of motor 24, the end 26 may move correspondingly while being continuously secured to the fuselage by track 30.

A strut 32; is pivotally connected at 34 with a swivel 36 mounted securely in the wing. The outer ends of legs 12 and M and leg 32 are secured together by a ball and socket joint 37 in a manner which will provide a rigid support for a. non-rotating pylon 38.

When motor 24 is actuated it operates through gearZZ and bearing 26 to swing truss leg 16 in an arc. Truss leg' 16 also rotates on its longitudinal axis by virtue of the fact that bushing 13 is rotatable in bearing 21). When the end 26 of truss leg 16 swings downward and forwardly to the position shown in Fig. 2, the inner end of rear leg 14 moves with it, causing strut 32 to swing rearwardly on swivel 36 to bring pylon 38 up against the fuselage. When motor 24 is actuated in the reverse direction, leg 16 again swings upward in the arc of the track 36 and pylon 38 is forced outward to its original position (Figs. 1, 3 and 4) by the change in position of rear leg 14.

The foundation members 4d and 44 which are rigidly afiixed to the junction of the truss members 12 and 14 support a bearing race 46 within which is a cooperating rotatable bearing member 46 to which is affixed the hub 50 of the rotor generally referred to as 52. The rotor has two blades 54 and 56 of which the leading edge of blade 54 is at 58 in Fig. 4 and the leading edge of blade '6 is at 60.

The rotor blades 54 and 56 are jet propelled, but as far as the present invention is concerned which involves the changing of the pitch of the blades, the blades could be mechanically driven in the manner disclosed in my copending application above referred to.

As can best be seen in Fig. 4, blade 54 is pivotally mounted on hub 50 by the tubular pivoting element 62 which is fixed in the hub and extends well into the blade. Similarly, blade 56 is mounted on the tubular pivot 64 which likewise is supported by hub 50 and extends a substantial distance into blade 56.

Attached to the hub end of pivot 62 is a lever 66 and to the hub end of pivot 64 is a lever 68. By moving levers 66 and 68 up and down within the confines of hub St) the pitch of blades 54 and 56 can be varied. If levers 66 and 63 are moved equally, the pitch of the two blades will likewise change equally. The mechanism that is utilized to cause movement of levers 66 and 68 will now be explained.

Referring now to Figs. 3, 5, 6 and 7, the floor of the pilot cockpit is shown at 7t). A lever 72 is utilized for causing collective pitch control, by which is meant that upon backward or forward movement of lever '72, the pitch of the blades of both port and starboard rotors is correspondingly increased or decreased. This lever is pivoted on a bracket at 74. Movement of lever 72 forward or backward will cause corresponding backward or forward movement of a piston 75 in cylinder 76. if lever 72 is moved backward, for example, the iluid 7%; in cylinder 76 will be forced into cylinder 30 through port 81 thereby causing the pistons 62 and 84 to spread apart against the influence of tension spring 66. Such movement of pistons 82 and 84 will cause flow of fluid from cylinder 86 through pipes 38 and 9% as follows. Liquid will flow in turn through pipe $8, pipe 92, and pipe 94, and thence into cylinder f6 to move piston 98 to the right (as seen in Fig. 5), and compressing spring 117 still further, spring 117 being normally under compression when lever 72 is in its vertical at rest position. The right end of cylinder 96 is vented to the atmosphere by a port 119. When the hydraulic pressure forces piston 98 to the right, lever 1% and bell crank 1M; are moved clockwise, causing rod 1% to move downwardly within the non-rotating pylon 38. The upper end of rod Hi4 carries a cross-bar 106 having rollers 1.01 on the ends thereof. The cross bar 1% does not rotate with the rotor but the rollers 101 on the ends engage with a rotating circular track 163 secured by studs 105 and 167 to the levers 66 and 68. Thus, as rod 1% is moved downwardly, the levers 66 and 68 move downwardly and the pitch of the blades 54 and 56 will be increased.

A similar construction is present in the other rotor so that rearward movement of lever 72 will cause simultaneous and equal increase in the pitch of the port and starboard rotors. This result is accomplished by fluid flowing from cylinder 80 through pipes 90 and 91 to a cylinder at the other rotor similar to cylinder 96.

When lever 72 is again returned to its normal vertical position, the fluid pressure on piston 98 is reduced to its original value and the piston is caused to move toward the left and restored to its original position by spring 117. When this occurs lever 1456 and bell crank 102 will move counterclockwise to restore the blades to their original pitch, i. e., the pitch prior to backward movement of lever 72.

To reduce the pitch of blades 54 and 56 still more, lever 72 is moved forwardly from its vertical position, causing piston 75 to move to the rear of cylinder 76 and permitting pistons 82 and 84 to be drawn together by a spring 86. This causes a further reduction in pressure in lines 88, 92, and 94-, and permits spring 117 to push piston 98 still further to the left. Such movement causes rod 104- to move upwardly to cause blades 54 and 56 to assume angles of reduced pitch. The rotor on the opposite side of the machine will be correspondingly effected by virtue of the reduced pressure in lines 5H) and 91.

It is believed clear, therefore, from the foregoing description that movement of lever 72 backward will increase the pitch of the rotor blades to cause the machine to rise whereas movement forward will cause the pitch of the blades to decrease thereby producing less lift in the rotors causing the machine to descend.

In order to produce differential lift of the rotors to correct for roll, another lever 31% is provided. This lever is pivoted at 110 and causes actuation of piston 112 in cylinder 114. Hereinafter, it will be understood that when reference is made to lever 108 being moved to the right or left, it Will be considered as viewed in Figs. 3 and 7. The said lever 163, however, as viewed by the pilot as he looks forward will be moved conversely to the left or right. Movement of lever 1% to the right will cause piston 112 to move to the left, reducing the pressure in line 94 and forcing liquid out of cylinder 114 into line 116. Due to the reduction in pressure in line 94 and hence on piston 98, the latter is moved by spring 117 to the left, causing counterclockwise motion of lever and bell crank M2 to reduce the pitch of blades 54 and 56. The increased pressure in line 116 is transmitted via line 91 to the piston associated with the opposite rotor to cause an increase in the pitch of its blades. in other words, the pitch of the blades of one rotor is increased while the pitch of the blades of the opposite rotor is simultaneously decreased. Movement of lever 108 to the left will result in an increase in pitch of blades 54 and 56 and a decrease in the pitch of the blades of the opposite rotor, thereby restoring the blades of both rotors to their original pitch. in other words, when lever 108 is moved to the left, the lift on one side of the machine is increased and on the other side is decreased to cause appropriate correction for roll. When lever 108 is moved to the right, the opposite effect is achieved.

From the foregoing description it can be seen that a pilot utilizing the two control sticks 72 and 108 can. change the pitch of the rotors at will, either collective ly or differentially, or in combination, and in this way the lift at the port and starboard rotors may be increased or decreased equally or increased on one side and decreased on the other side.

The provision of the swivel joint 118 in the fluid line 94 permits the rotor to be stored in the manner described in my above identified co-pending application without interfering in any way with the subsequent operation of piston 98. A similar swivel joint is present in line 91 on the starboard side of the machine.

Means for stopping and locking rotor Referring to Fig. 8, there is shown schematically the arrangement of the braking system and in Fig. 5 there is shown an enlarged sectional detail of the brake of the port rotor. The braking system can be either manually controlled or driven by a pump at the users option. The

manually controlled system will be considered as sufficiently illustrative.

Referring to Fig. 8 there is shown a brake lever 130 connected with piston 132 in cylinder 134. Liquid 136 is in the cylinder and the piping 13%. Movement of brake lever to the left will cause fluid to how through pipe 138 to the brake cylinders 140 and 142 to spread the brake shoes 144 and 146 to press against the interior of brake drums 148 and 150, thus stopping both port and starboard rotors simultaneously.

On referring to the detailed sectional view of Fig. 5, the liquid under pressure flows through pipe 13% to the brake cylinder 140 not shown, causing the spreading of brake shoes 144 against the brake drum 148 which is integral with the hub 50. In this way the rotor 52. is brought to a halt.

Since the rotor when stopped may not be positioned at the correct angle for stowing, a hydraulic motor 152 is provided for causing slow rotation of the rotor until the stowing position is reached. This motor has on its shaft a gear 154 which meshes with a corresponding gear 156 attached to brake drum 148. Motor 152 is then actuated by feeding liquid under pressure to it through pipes not shown, all in a conventional manner as through a motor driven oil pump causing slow rotation of rotor 52.

The liquid line running to motor 152 has a short branch 158 which terminates in cylinder 168 causing piston 162 to move upwardly against the pressure of spring 164 simultaneously with the application of the motor. In this way the pin 166 is extended upwardly and will snap into a suitable hole on the under side of rotor 52 as soon as the rotor has been turned sufilciently by the motor 152 to bring the pin 166 and the hole 167 into alignment.

The brake 144 which had been released during the period of operation of motor 152. is now reapplied to hold the rotor in correct position while it is being stowed through the movement of the rotor supporting truss described in my copending application.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. Therefore, it is to be understood that the in vention is not limited in its application to the details of construction and arrangement of parts specifically described or illustrated, and that within the scope of the appended claims it may be practiced otherwise than as specifically described or illustrated.

I claim:

1. In a convertiplane having a fuselage, a single wing and pair of rotors vertically spaced with respect to said wing, said rotors being movable from an operating position spaced laterally of said fuselage to a stowed position up against said fuselage, means for swinging said rotors from said operating position to said stowed position, a source of power for causing said rotors to rotate, and means for simultaneously varying the pitch of the blades of said rotors while said rotors are in operation.

2. In a convertiplane having a fuselage, a single wing a pair of rotors vertically spaced with respect to said wing, said rotors being swingable from an operating position spaced laterally of said fuselage to a stowed position up against said fuselage, and means for swinging said rotors from said operating position to said stowed position, a source of power for causing said rotors to rotate, and means for simultaneously increasing the pitch of the blades of one rotor and decreasing the pitch of the blades of the other rotor while said rotors are in operation.

3. The structure set forth in claim 1, said means for varying the pitch of said rotors comprising a hydraulic system including master and slave cylinders and linkages operated thereby for causing simultaneous movement of both blades of each rotor.

4. The structure set forth in claim 2, said means for increasing the pitch of the blades of one rotor and decreasing the pitch of the blades of the other rotor, com prising a hydraulic system including master and slave cylinders and linkages operated thereby for causing simultaneous movement of both blades of each rotor.

5. The structure set forth in claim 1, a brake for causing each rotor to come to a halt after the said power source has been discontinued, means for thereafter moving each said blade slowly to the correct position for stowing and means for holding said blade in said correct position while it is being stowed.

6. The structure set forth in claim 5, said means for moving said rotors to correct stowing position comprising a hydraulic motor mounted adjacent each of said brakes.

7. In a convertiplane having a fuselage, a. single Wing and a pair of helicopter rotors vertically spaced with respect to said wing, said rotors being movable from an operating position spaced laterally of said fuselage to a stowed position up against said fuselage means for causing rotation of said rotors, each said rotor having a rotor hub and blades pivotally mounted with respect to said rotor hub, two sets of manually operable controls, one set of said controls comprising a hydraulic system having a master and slave cylinders which move in like manner under the influence of said master cylinder and linkages operated by said slave cylinders for causing simultaneous movement of the blades of both rotors in the same direction, said other set of controls comprising a second master cylinder connected to said same slave cylinders so that said slave cylinders move in unlike manner under the influence of said second master cylinder whereby said linkages operated thereby and connected to said rotor blades will simultaneously increase the pitch of the blades of one rotor and decrease the pitch of the blades of the other rotor and means for stopping the rotation of said rotors and thereafter moving said rotors to proper position for subsequent stowing against the fuselage of said convertiplane.

8. The structure set forth in claim 7, said means for stopping the rotation of said rotors being hydraulically operated and said means for moving said blades to cor rect stowing position comprising a hydraulically operated motor.

9. In a convertiplane having a fuselage, a single wing and a pair of rotors vertically spaced with respect to said wing, said rotors being movable from an operating position spaced laterally of said fuselage to a stowed position up against said fuselage means for moving said rotors from said operative to said stowed position, means for stopping said rotors at the correct position for stowing, means for locking said rotors in correct stopped position, control means for causing collective pitch control of the blades of said rotors, and other control means for causing differential pitch control of the blades of said rotors.

References Cited in the tile of this patent UNITED STATES PATENTS 2,021,470 Upson Nov. 19, 1935 2,284,902 Hosford June 2, 1942 2,411,297 Serna Nov. 19, 1946 

